PA5542 (Q9HT32, PIB-1) review notes

No deep-research provider was available. Sources: UniProt record (TrEMBL, with PDB 8RLJ/8RLK/8RLL),
cached PMID:25185138 (abstract only) and PMID:39097051 (abstract only, fetched for this review).
PubMed searches through the MCP ("PA5542 imipenemase", 2026-11-05) returned no hits (search service
failing), so the literature beyond these two papers was not surveyed.

Function

Purified PA5542 hydrolyses imipenem; zinc stimulates it
PMID:25185138.
Knockout raises, overexpression lowers carbapenem susceptibility
PMID:25185138.
Structures place PIB-1 in class C beta-lactamases; carbapenems but not cephalosporins are degraded;
metal ions do not bind the active site but promote more active trimers
PMID:39097051.
Sequence: SignalP signal peptide 1-25; PF00144 domain 94-408; S-x-x-K motif SVVK at residue 131
(checked on the UniProt sequence). PANTHER PTHR43283:SF14.

PseudoCAP IBA-seed assessment

PTN node	node term	n_seeds	leaf IBAs	seed annotation (term, evidence, PMID)	verdict	rationale	other seeds	IBD stands without this seed?
PTN009168613	GO:0016787 hydrolase activity	3	68 (26 taxa)	GO:0008800 beta-lactamase activity, IDA, PMID:25185138 (PseudoCAP)	SOUND	Purified enzyme hydrolyses imipenem in a spectrophotometric assay (abstract); confirmed by the 2024 structural/functional paper. The generic hydrolase node term suits a PF00144 clade of penicillin-binding-fold hydrolases.	E. coli PBP4B/YfeW P77619 (IDA DD-carboxypeptidase, PMID:16402224); B. subtilis AmiE/YbbE O05213 (EXP N-acetylmuramyl-L-alanine amidase, PMID:20400549)	Yes; both other seeds carry experimental hydrolase descendants. No GO_CENTRAL defect.

Defects recorded: PSEUDOCAP 0; GO_CENTRAL 0.